Knowledge about the nature of prostatic secretion and the processes by which it is formed is critically important, especially with respect to understanding two human prostatic diseases - prostatitis and prostatic adenocarcinoma. With the possible exception of the canine prostate, which has been the subject of a number of studies by the applicant, there is suprisingly little information about the processes involved in prostatic fluid formation. The objectives of the proposal experiments are to further characterize the chemical composition of canine prostatic fluid, particularly its flow-dependence and to document the changes in composition which result from a number of carefully selected interventions. The interventions or procedures to be employed include (1) selectively damaging ductal portions of the gland with mercuric chloride, (2) applying stop-flow techniques, (3) elevating intraluminal pressure, (4) administering drugs known to interfere with many transport processes and secretory systems, (5) producing systemic acidosis and alkalosis, and (6) study some aspects of secretion in vitro. The results of these experiments will provide new knowledge about the fundamental processes involved in prostatic fluid formation and aspects of these experiments will lead to a better understanding of the interaction between the prostate and foreign chemicals.